Lighting assembly with defined angular output

ABSTRACT

A lighting assembly includes a light guide and solid-state light emitters to edge-light the light guide, the light emitters arrayed along a transverse direction. The light guide includes two or more sets of optical elements of well-defined shape. Light output from the lighting assembly by the first and second set of optical elements have a first and a second light ray angle distribution, respectively. The optical elements are configured such that when measured in a plane perpendicular to the light guide and the transverse direction: 1) the first and second light ray angle distributions are significantly narrower than an omnidirectional output distribution; and 2) the peak of the second light ray angle distribution is displaced from the peak of the first light ray angle distribution.

RELATED APPLICATION DATA

This application claims the benefit of U.S. Provisional PatentApplication No. 61/732,112, filed Nov. 30, 2012 and U.S. ProvisionalPatent Application No. 61/869,129, filed Aug. 23, 2013, the disclosuresof which are herein incorporated by reference in their entireties.

BACKGROUND

Light emitting diodes (LEDs) show promise as an energy efficient lightsource for lighting assemblies. For some LED-based lighting assemblies,the light emitted from the light source is input to a light guide andmicro-optical elements extract the light from the light guide in defineddirections. In particular, efficiency of providing light with a definedangular distribution to illuminate the area of interest is desired formany applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a first exemplary lightingassembly.

FIG. 2 is a schematic side view of the first exemplary lighting assemblyof FIG. 1.

FIG. 3 is a schematic perspective view of a second exemplary lightingassembly.

FIGS. 4A, 5A, and 6A are schematic cross-sectional views of exemplaryfootball-shaped micro-optical elements.

FIGS. 4B, 5B, and 6B are polar plots of light ray angle distributionsfrom lighting assemblies using the football-shaped micro-opticalelements of FIGS. 4A, 5A, and 6A, respectively.

FIG. 7 is a polar plot of a light ray angle distribution from a lightingassembly using the football-shaped micro-optical elements of FIGS. 4Aand 6A.

FIG. 8 is a polar plot of a light ray angle distribution from a lightingassembly using the football-shaped micro-optical elements of FIGS. 4A,5A, and 6A.

FIGS. 9-13 are polar plots of light ray angle distributions fromlighting assemblies using other football-shaped micro-optical elements.

FIGS. 14A and 14B are schematic plan and side views of anothermicro-optical element.

FIG. 14C is a polar plot of a light ray angle distribution from alighting assembly using the micro-optical element of FIG. 14A.

FIG. 15 is a polar plot of a light ray angle distribution from alighting assembly using the micro-optical elements of FIGS. 14A and 6A.

FIG. 16 is a schematic perspective view of a third exemplary lightingassembly.

DESCRIPTION

Embodiments will now be described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. The figures are not necessarily to scale. Features that aredescribed and/or illustrated with respect to one embodiment may be usedin the same way or in a similar way in one or more other embodimentsand/or in combination with or instead of the features of the otherembodiments. In this disclosure, angles of incidence, reflection, andrefraction and output angles are measured relative to the normal to thesurface.

With initial reference to FIGS. 1 and 2, a first exemplary lightingassembly is shown at 10. The lighting assembly 10 includes an opticalsubstrate embodied as a light guide 12. The light guide 12 is a solidarticle of manufacture made from, for example, polycarbonate,poly(methyl-methacrylate) (PMMA), or other appropriate material. Thelight guide 12 may also be a multi-layer light guide having two or morelayers that may differ in refractive index. The light guide 12 includesa first major surface 26 and a second major surface 28 opposite thefirst major surface 26. The first major surface 26 is shown as a topmajor surface and the second major surface is shown as the bottom majorsurface. The terms top and bottom are relative to an orientation of thelighting assembly 10. Relative nomenclature for aspects of the lightingassembly 10 may change with changes in orientation of the lightingassembly 10. Therefore, terms such as top and bottom are used in thisdisclosure for descriptive purposes only.

The light guide 12 is configured to propagate light by total internalreflection between the first major surface 26 and the second majorsurface 28. The length and width dimensions of each of the majorsurfaces 26, 28 are greater, typically ten or more times greater, thanthe thickness of the light guide 12. The thickness is the dimension ofthe light guide 12 in a direction 40 (FIG. 2) perpendicular to the majorsurfaces 26, 28.

At least one edge surface extends between the major surfaces 26, 28 ofthe light guide in the thickness direction. The total number of edgesurfaces depends on the configuration of the light guide. In the casewhere the light guide is rectangular, the light guide has four edgesurfaces 14, 16, 18, and 32. Other light guide shapes result in acorresponding number of side edges. Depending on the shape of the lightguide 12, each edge surface may be straight or curved, and adjacent edgesurfaces may meet at a vertex or join in a curve. Moreover, each edgesurface may include one or more straight portions connected to one ormore curved portions. The edge surface 14 through which light from thelight sources 22 is input to the light guide will now be referred to asa light input edge. The light that enters through the light input edge14 propagates by total internal reflection at the major surfaces 26, 28towards the edge distal the light input edge 14, referred to as thedistal edge 32. In some embodiments, the light guide 12 includes morethan one light input edge; for example, the distal edge 32 can be usedas a second light input edge. The edges 16 and 18 are referred to asside edges. In the illustrated embodiment, the major surfaces 26, 28 areplanar and substantially parallel to each other.

The lighting assembly 10 includes a light source 22 positioned adjacentthe light input edge 14. The light source 22 is configured to edge lightthe light guide 12 such that light from the light source enters thelight input edge 14 and propagates along the light guide 12 by totalinternal reflection at the major surfaces 26, 28. In this example, thelight source 22 includes solid-state light emitters 24. The solid-statelight emitters 24 constituting the light sources 22 are arrangedlinearly (linear array) or in another suitable pattern depending on theshape of the light input edge 14 of the light guide 12 to which thelight source 22 supplies light. In the example of FIGS. 1 and 2, thereare three solid-state light emitters 24 and they are arrayed in a linealong the light input edge 14 in a direction 20, which is given by anintersection of the light input edge 14 and one of the major surfaces26, 28. We also refer to direction 20 as the transverse direction. Inthis example, the solid-state light emitters are white light emittingLEDs. Direction 30 is perpendicular to direction 20 and extends betweenthe light input edge 14 and distal edge 32. More generally, direction 30is a direction perpendicular to the transverse direction (direction 20)in which the light guide 12 extends away from the light input edge 14.We also refer to direction 30 as the longitudinal direction. Directions20 and 30 are parallel to a plane that includes major surface 26 or 28.Furthermore, directions 20 and 30 are perpendicular to direction 40.Generally we refer to the dimension of the light guide along direction30 (longitudinal direction) as the length of the light guide and to thedimension of the light guide along direction 20 (transverse direction)as the width of the light guide.

The light guide 12 includes micro-features of well-defined shapeembodied as micro-optical elements 60 in, on, or beneath at least one ofthe major surfaces 26, 28. Micro-optical elements that are in, on, orbeneath a major surface will be referred to as being “at” the majorsurface. The micro-optical elements 60 are features of well-definedshape that predictably reflect or refract the light propagating in thelight guide 12. In some embodiments, at least one of the micro-opticalelements 60 is an indentation in the major surface 26, 28 ofwell-defined shape. In other embodiments, at least one of themicro-optical elements 60 is a protrusion from the major surface 26, 28of well-defined shape. In the example of FIGS. 1 and 2, themicro-optical elements 60 are indentations on the first major surface(top major surface) 26.

A micro-optical element of well-defined shape is a three-dimensionalfeature recessed into a major surface or protruding from a majorsurface. Micro-optical elements of well-defined shape exclude featuresof indistinct shape or surface textures, such as printed features ofindistinct shape, ink-jet printed features of indistinct shape,selectively-deposited features of indistinct shape, and features ofindistinct shape wholly formed by chemical etching or laser etching.

Each micro-optical element 60 functions to disrupt the total internalreflection of the light propagating in the light guide and incidentthereon. In one embodiment, the micro-optical elements 60 reflect lighttoward the opposing major surface so that the light exits the lightguide 12 through the opposing major surface. Alternatively, themicro-optical elements 60 transmit light through the micro-opticalelements 60 and out of the major surface of the light guide 12 havingthe micro-optical elements 60. In another embodiment, both types ofmicro-optical elements 60 are present. In yet another embodiment, themicro-optical elements 60 reflect some of the light and refract theremainder of the light incident thereon. Therefore, the micro-opticalelements 60 are configured to extract light from the light guide 12through one or both of the major surfaces 26, 28. The micro-opticalelements 60 are sometimes referred to as light extracting elements.

In the example of FIGS. 1 and 2, the micro-optical elements 60 reflectsome of the light and refract some of the light incident thereon.However, as illustrated in FIG. 2, there is a back reflector 44 adjacentto and juxtaposed with the first major surface 26 which reflects most ofthe light extracted through the first major surface 26 back toward thelight guide 12. Therefore, most of the light is output from the lightingassembly 10 through the second major surface 28. This configurationcould be used, for example, as a lighting assembly that is suspendedfrom or recessed into a ceiling. The reflector 44 can also be configuredto reflect a fraction of the light and transmit the remainder of thelight. Additionally, as shown in FIG. 2, there is a distal edgereflector 46 adjacent to and juxtaposed with the distal edge 32, whichreflects most of the light passing through the distal edge 32 back intothe light guide. Similarly, side edge reflectors (not shown) can beplaced adjacent to and juxtaposed with the side edges 16, 18. The backreflector 44 and distal edge reflector 46 are shown omitted in FIG. 1.

The micro-optical elements 60 are configured to extract light with adefined light ray angle distribution from one or both of the majorsurfaces 26, 28. In this disclosure, the term light ray angledistribution is used to describe the variation of the intensity of lightwith ray angle (typically a solid angle) over a defined range of lightray angles.

Micro-optical elements 60 are small relative to the linear dimensions ofthe major surfaces 26, 28. The smaller of the length and width of amicro-optical element 60 is less than one-tenth of the longer of thelength and width (or circumference) of the light guide 12 and the largerof the length and width of the micro-optical element 60 is less thanone-half of the smaller of the length and width (or circumference) ofthe light guide 12. The length and width of the micro-optical element 60is measured in a plane parallel to the major surface 26, 28 of the lightguide 12 for planar light guides or along a surface contour fornon-planar light guides 12.

Light guides 12 having micro-optical elements 60 are typically formed bya process such as injection molding. Injection molding is known in theart, and typically utilizes a patterning tool for forming themicro-optical elements 60 at the major surface 26, 28 of the light guide12.

In the example of FIGS. 1 and 2, the light guide 12 has three lightoutput regions 34, 36, and 38, arrayed along direction 30, which is thelongitudinal direction of the light guide 12. The light guide has atransition region 42 where the light from the light sources mixes andspreads after the light enters the light guide through the light inputedge 14 and before the light reaches light output regions 34, 36, and38. Each light output region 34, 36, and 38 has micro-optical elements100, 120, and 135, respectively. The reference numeral 60 will begenerally used to collectively refer to the different embodiments ofmicro-optical elements. FIG. 1 illustrates an example where the lightguide 12 has distinct light output regions where each light outputregion has micro-optical elements of nominally identical shape.Alternatively, micro-optical elements of different shapes are mixed in alight output region, as shown in FIG. 3. FIG. 3 illustrates a secondexemplary lighting assembly 50 in which the light guide 12 has a lightoutput region 54 in which micro-optical elements 60 of different shapesare mixed.

The micro-optical elements 100, 120, and 135 are examples ofmicro-optical elements 60 configured as V-groove-shaped depressionshaving an arcuate ridge, hereinafter referred to as “football-shaped,”due to similarities in general appearance to part of an American-stylefootball. Such micro-optical elements may alternatively be configured asV-groove-shaped protrusions with an arcuate ridge. Each football-shapedmicro-optical element 60 includes a first side surface 102 and a secondside surface 104 that come together to form a ridge 106 having ends thatintersect the one of the major surfaces 26, 28 at which themicro-optical element 60 is formed. In the example of FIGS. 1 and 2, theridges 106 generally extend along direction 20, such that the first sidesurfaces 102 face toward the linear array of solid-state light emitters24. The reference numeral 102 will be generally used to collectivelyrefer to the different embodiments of the first side surface, and thereference numeral 104 will be generally used to collectively refer tothe different embodiments of the second side surface. For eachmicro-optical element, the first side surface 102 is closer to the lightinput edge 14 than is the second side surface 104. We also refer to thefirst side surface as the leading side surface and the second sidesurface as the trailing side surface.

A cross-section of micro-optical element 100, 120, 135, taken along thedirection 30 (light guide length direction) at the location of itsmaximum width and depth, is shown in FIGS. 4A, 5A, 6A. The acuteincluded angle 100A, 120A, 135A formed by the first side surface 102 andsecond side surface 104 is 100°, 120°, 135°, respectively. We refer tothe length of the ridge 106 parallel to the major surface 26 at whichthe micro-optical element is located (in this case generally alongdirection 20, the light guide transverse direction) as the length of themicro-optical element 100, 120, 135; the dimension in the direction 40(light guide thickness direction) as the depth (or height); and thedimension parallel to the major surface 26, 28 at which themicro-optical element is located perpendicular to its length (in thiscase generally along direction 30, the light guide longitudinaldirection) as and the width. Using these conventions, all of themicro-optical elements 100, 120, 135 in the illustrated, exemplaryembodiment have a nominal length of approximately 0.290 mm and a nominaldepth of approximately 0.022 mm. The micro-optical elements 100, 120,135 in the illustrated, exemplary embodiment have nominal widths ofapproximately 0.052 mm, 0.076 mm, and 0.106 mm. These micro-opticalelements are elongate and oriented in direction 20 (transversedirection). Note also that in this example, the micro-optical elements100, 120, 135 are indented symmetrically into the light guide; i.e., themicro-optical elements are not tilted to or away from the light inputedge 14 (neither tilted to the right nor to the left relative to thefirst major surface 26 in FIGS. 4A, 5A, 6A).

FIG. 4B is a polar plot of the far-field light ray angle distribution200 of light extracted from a lighting assembly similar to the lightingassembly of FIGS. 1 and 2, except that the light guide 12 only hasmicro-optical elements 100 (football-shaped elements with included angleof 100°). The light ray angle distribution 200 is measured in ameasurement plane perpendicular to the light input edge (transversedirection) and at least one of the major surfaces 26, 28 of the lightguide. Since the major surfaces 26, 28 are substantially parallel toeach other in many cases, one of the major surfaces 26, 28 can be chosenby convenience. The light source 22 is arranged at −90°, the first majorsurface 26 (top major surface) is arranged proximate 180°, and thesecond major surface 28 (bottom major surface) is arranged proximate 0°.The light output is through the second major surface (bottom majorsurface) because of the back reflector proximate the first major surface26 (top major surface). The light output is generally away from thelight sources, and the peak angle is approximately 6°. A full-width athalf maximum (FWHM) is approximately 24°. Polar plots of far-field lightray angle distributions 220, 235 of light extracted from similarlighting assemblies that only have micro-optical elements 120, 135 areshown in FIGS. 5B, 6B, respectively. For micro-optical elements 120(included angle 120°) and 135 (included angle 135°), the peak angles are20° and 35° , respectively, and the FWHM values are 38° and 44°,respectively. These light ray angle distributions are significantlynarrower than an omnidirectional output distribution. For example,omnidirectional output distributions are obtained from light emittingassemblies having light extracting features of indistinct shape. For anideal Lambertian omnidirectional output, the FWHM would be 120°.

FIG. 7 is a polar plot of a far-field light ray angle distribution 60 oflight extracted from a lighting assembly in which 50% of themicro-optical elements are micro-optical elements 100 (football-shapedelements with included angle 100°) and 50% of the micro-optical elementsare micro-optical elements 135 (football-shaped elements with includedangle 135°). There are two peaks in the light ray angle distribution 60attributable to each of the micro-optical elements 100, 135 with a “gap”between them where the intensity is relatively low. In someapplications, light ray angle distributions that do not have such “gaps”are preferred.

FIG. 8 is an example of a light ray angle distribution arising fromthree micro-optical element shapes (100, 120, 135) instead of twomicro-optical element shapes (100, 135) as in FIG. 7. FIG. 8 is a polarplot of a far-field light ray angle distribution 62 of light extractedfrom a lighting assembly in which 25% of the micro-optical elements aremicro-optical elements 100 (football-shaped elements with included angle100°), 25% of the micro-optical elements are micro-optical elements 120(football-shaped elements with included angle 120°), and 50% of themicro-optical elements are micro-optical elements 135 (football-shapedelements with included angle 135°). By adjusting the selection andproportion of micro-optical elements, the light ray angle distributioncan be adjusted. In particular, FIG. 8 illustrates an example of fillingin a “gap” in the light ray angle distribution by including anadditional micro-optical element shape.

The light ray angle distributions of lighting assemblies havingfootball-shaped elements with other included angles have also beenmeasured. FIGS. 9, 10, 11, 12, 13 are polar plots of the far-field lightray angle distributions (205, 210, 225, 230, 240) from 105°, 110°, 125°,130°, and 140° included angle football-shaped micro-optical elements,respectively. All of these football-shaped micro-optical elements have anominal length of approximately 0.290 mm and a nominal depth ofapproximately 0.022 mm. In all cases, they are oriented with the ridges106 in the transverse direction 20. The widths of these football-shapedmicro-optical elements vary according to the included angles. The peakangle and FWHM values for these football-shaped micro-optical elementsare summarized in Table 1 below. For each micro-optical element shapelisted in Table 1, the peak angle is displaced from those of othermicro-optical element shapes. For all football-shaped micro-opticalelement shapes listed in Table 1, the FWHM is significantly narrowerthan an omnidirectional light ray angle distribution.

TABLE 1 Optical element Peak angle (degrees) FWHM (degrees) Footballshaped, included  6 24 angle = 100° Football shaped, included 10 26angle = 105° Football shaped, included 15 24 angle = 110° Footballshaped, included 20 38 angle = 120° Football shaped, included 23 37angle = 125° Football shaped, included 28 45 angle = 130° Footballshaped, included 35 44 angle = 135° Football shaped, included 40 42angle = 140° Shape shown at 100R 11 82 Omnidirectional NA 120

FIGS. 14A and 14B illustrate a micro-optical element that produces alight ray angle distribution that is wider than the football-shapedmicro-optical elements described above and still significantly narrowerthan an omnidirectional light ray angle distribution. Micro-opticalelement 100R is shown in plan view in FIG. 14A and in side view from thelight input edge 14 in FIG. 14B. Micro-optical element 100R is elongatealong direction 20 (transverse direction), and has a first side surface92 (leading surface) and a second side surface 94 (trailing surface), inwhich the leading surface faces toward the linear array of light sources22. These micro-optical elements are elongate in direction 20(transverse direction). Instead of coming together to form a ridge,there is a rounded surface 96 connecting the first side surface 92 andthe second side surface 94. The rounded surface 96 is configured to betangential to the first side surface 92 and the second side surface 94.In other words, the rounded surface 96 is rounded in a plane thatincludes the longitudinal direction 30 and thickness direction 40. Werefer to the length of the rounded surface 96 parallel to the majorsurface 26 at which the micro-optical element is located (in this casegenerally along transverse direction 20) as the length of themicro-optical element 100R; the dimension in the thickness direction 40as the depth (or height); and the dimension parallel to the majorsurface 26, 28 at which the micro-optical element is locatedperpendicular to its length (in this case generally along longitudinaldirection 30) as and the width. Using these conventions, micro-opticalelement 100R has a nominal length of approximately 0.290 mm, a nominaldepth of approximately 0.022 mm, and a nominal width of approximately0.085 mm. For each micro-optical element 100R, the first side surface 92is closer to the light input edge 14 than is the second side surface 94.The rounded surface 96 is rounded with a radius of curvature of 0.045 mmin a plane that includes longitudinal direction 30 and thicknessdirection 40. The rounded surface 96 is arcuate such that its ends 93and 95 intersect the one of the major surfaces 26, 28 at which themicro-optical element 100R is formed. The length of the micro-opticalelement 100R is the distance between the rounded surface ends 93, 95.Even though the first side surface 92 and the second side surface 94 donot intersect, the included angle between them can be found by extendingthe first and second side surfaces toward each other. In this case, theincluded angle is 100°. These micro-optical elements are elongate andoriented in transverse direction 20. In comparison to thefootball-shaped micro-optical element 100 with included angle of 100°,the light ray angle distribution is broader because of the roundedsurface 96.

FIG. 14C is a polar plot of the far-field light ray angle distribution98 from micro-optical elements 100R. The peak angle and FWHM areincluded in Table 1. Compared to the 100° included angle football-shapedmicro-optical element, the FWHM has broadened from approximately 24° toapproximately 82°.

FIG. 15 illustrates a light ray angle distribution output from a thirdexemplary lighting assembly incorporating the rounded elongatemicro-optical element 100R. Specifically, FIG. 15 is a polar plot of afar-field light ray angle distribution 64 of light extracted from alighting assembly in which 50% of the micro-optical elements are roundedelongate micro-optical elements 100R and 50% of the micro-opticalelements are micro-optical elements 135 (football-shaped elements withincluded angle 135°). In comparison to the light ray angle distribution60 (FIG. 7), there is no observable gap in the light ray angledistribution because of the broader output of rounded micro-opticalelement 100R relative to the football-shaped micro-optical element 100.

As used herein, the term “shape” refers to the overall structure of themicro-optical element 60. Therefore, the micro-optical element 100 andthe micro-optical element 120 have different shapes. But, these twoelements are both of the same shape type in that they are both“football-shaped.” A “shape-type” refers to a combination of geometricfeatures (e.g., surfaces, included angles, ridge features, etc.) thatcombine to form the micro-optical element 60. If two micro-opticalelements 60 have the same combination of geometric features, butdifferent sizes for any those geometric features, then they areconsidered to have different shapes, but are of the same shape type.Other exemplary embodiments of the light guide 12 may includemicro-optical elements 60 having other suitable shapes and/or shapetypes. Exemplary micro-optical elements 60 are described in U.S. Pat.No. 6,752,505, the entire content of which is incorporated by reference,and, for the sake of brevity, are not described in detail in thisdisclosure. Exemplary other possible shape types include, but are notlimited to, V-grooves (e.g., two planar surfaces that intersect at astraight ridge), truncated cones, wedges, the element of FIGS. 14A and14B discussed above, etc. The micro-optical elements 60 for the lightguide 12 may be all of the same shape type (e.g., football-shaped oranother shape type). Alternatively, a mix of shapes types may beemployed (e.g., truncated cones and V-grooves). Typically, each lightoutput region (e.g., regions 34, 36, and 38) will respectively includemicro-optical elements 60 with the same shape. In other embodiments, oneor more of the light output regions (e.g., regions 34, 36, and 38)include micro-optical elements 60 with a mix of shapes that are all ofthe same shape type. In still other embodiments, one or more of thelight output regions (e.g., regions 34, 36, and 38) includemicro-optical elements 60 with a mix of shapes types.

Additionally, well-defined optical elements that are larger thanmicro-optical elements can be used, an example of which is shown in FIG.16. FIG. 16 is a schematic perspective view of a third lighting assembly70, which is similar to the first lighting assembly 10 (FIG. 1). Thelight guide 12 has three light output regions 74, 76, and 78, arrayedalong the light guide longitudinal direction 30. The light guide has atransition region 42 where the light from the light sources 22 mixes andspreads after the light enters the light guide through the light inputedge 14 and before the light reaches light output regions 74, 76, and78. Each light output region 74, 76, and 78 has elongate opticalelements 84, 86, 88, respectively, configured as V-groove-shapeddepressions having a ridge. Such optical elements may alternatively beconfigured as V-groove-shaped protrusions with a ridge. As shown, eachoptical element extends across most of the transverse dimension(direction 20) of the light guide 12. The optical elements can extendacross ninety percent (90%) or more of the transverse dimension of thelight guide 12. Although not illustrated in detail, optical elements 84,86, and 88 include a first side surface (leading side surface) and asecond side surface (trailing side surface) that come together to form aridge. In the example of FIG. 16, the ridges generally extend alongtransverse direction 20, such that the first side surfaces face towardthe linear array of light sources 22. The optical elements 84, 86, and88 differ in that the included angles formed by the first and secondside surfaces differ. For example, the included angles in opticalelements 84 can be 135°, the included angles in optical elements 86 canbe 120°, and the included angles in optical elements 88 can be 100°. Insuch case, a cross section taken across the light guide in the lightguide length direction (direction 30) would appear similar to FIGS. 4A,5A, and 6A. The optical elements 84, 86, and 88 are sometimes referredto as light extracting elements.

Lighting assemblies in accordance with the present disclosure areconfigurable for use in various applications and may include additionalcomponents. For example, although not specifically shown in detail, insome embodiments of the lighting assembly, the light source 22 includesstructural components to retain the solid-state light emitters 24 andthe solid-state light emitters 24 can be mounted to a printed circuitboard (PCB). The light source 22 may additionally include circuitry,power supply, electronics for controlling and driving the solid-statelight emitters 24, and/or any other appropriate components.

Exemplary solid-state light emitters 24 include such devices as LEDs,laser diodes, and organic LEDs (OLEDs). In an embodiment where thesolid-state light emitters 24 are LEDs, the LEDs may be top-fire LEDs orside-fire LEDs, and may be broad spectrum LEDs (e.g., white lightemitting LEDs) or LEDs that emit light of a desired color or spectrum(e.g., red light, green light, blue light, or ultraviolet light), or amixture of broad-spectrum LEDs and LEDs that emit narrow-band light of adesired color. In one embodiment, the solid-state light emitters 24 emitlight with no operably-effective intensity at wavelengths greater than500 nanometers (nm) (i.e., the solid-state light emitters 24 emit lightat wavelengths that are predominantly less than 500 nm). In someembodiments, the solid-state light emitters 24 constituting light source22 all generate light having the same nominal spectrum. In otherembodiments, at least some of the solid-state light emitters 24constituting light source 22 generate light that differs in spectrumfrom the light generated by the remaining solid-state light emitters 24.For example, two different types of solid-state light emitters 24 arealternately located along the light source 22.

In some embodiments, the lighting assembly 10 is a part of a lightingfixture, a sign, a light bulb (e.g., A-series LED lamp or PAR-type LEDlamp), or an under-cabinet lighting fixture (e.g., lighting fixture foruse under kitchen cabinets).

In this disclosure, the phrase “one of” followed by a list is intendedto mean the elements of the list in the alterative. For example, “one ofA, B and C” means A or B or C. The phrase “at least one of” followed bya list is intended to mean one or more of the elements of the list inthe alterative. For example, “at least one of A, B and C” means A or Bor C or (A and B) or (A and C) or (B and C) or (A and B and C).

What is claimed is:
 1. A lighting assembly, comprising: a plurality ofsolid-state light emitters; a light guide comprising a light input edgeadjacent the light emitters, a first major surface and a second majorsurface opposite the first major surface, a first set of opticalelements of well-defined shape positioned at one of the major surfaces,and a second set of optical elements of well-defined shape positioned atone of the major surfaces, wherein light from the light emitterspropagates in the light guide by total internal reflection at the majorsurfaces, light output from the lighting assembly by the first set ofoptical elements has a first light ray angle distribution and lightoutput from the lighting assembly by the second set of optical elementshas a second light ray angle distribution, the light emitters beingarrayed along the light input edge in a transverse direction, and ameasurement plane being defined to be perpendicular to the transversedirection and to the first major surface or the second major surface ofthe light guide; wherein: the first light ray angle distribution in themeasurement plane is significantly narrower than an omnidirectionaloutput distribution and the second light ray angle distribution in themeasurement plane is significantly narrower than an omnidirectionaloutput distribution; a peak of the second light ray angle distributionin the measurement plane is displaced from a peak of the first light rayangle distribution in the measurement plane; each of the opticalelements of the first set comprises a first leading surface and a firsttrailing surface, the first leading surface and the first trailingsurface forming a first included angle; each of the optical elements ofthe second set comprises a second leading surface and a second trailingsurface, the second leading surface and the second trailing surfaceforming a second included angle; and the first included angle differsfrom the second included angle.
 2. The lighting assembly of claim 1,wherein the first set of optical elements and the second set of opticalelements are both positioned at the same one of the first major surfaceor the second major surface.
 3. The lighting assembly of claim 1,additionally comprising a third set of optical elements of well-definedshape positioned at one of the major surfaces, light output from thelighting assembly by the third set of optical elements has a third lightray angle distribution; wherein: the third light ray angle distributionin the measurement plane is significantly narrower than anomnidirectional output distribution; a peak of the third light ray angledistribution in the measurement plane is displaced from a peak of thefirst light ray angle distribution in the measurement plane; and a peakof the third light ray angle distribution in the measurement plane isdisplaced from a peak of the second light ray angle distribution in themeasurement plane.
 4. The lighting assembly of claim 1, wherein at leastone of the first light ray angle distribution or the second light rayangle distribution in the measurement plane has a full width at halfmaximum of less than 90°.
 5. The lighting assembly of claim 4, whereinat least one of the first light ray angle distribution or the secondlight ray angle distribution in the measurement plane has a full widthat half maximum of less than 45°.
 6. The lighting assembly of claim 1,wherein a peak of the second light ray angle distribution in themeasurement plane is displaced from a peak of the first light ray angledistribution in the measurement plane by 10° or more.
 7. The lightingassembly of claim 1, wherein the optical elements of at least one of thefirst set or the second set are elongate in the transverse direction. 8.The lighting assembly of claim 1, wherein the first leading surface iscloser to the light input edge than is the first trailing surface foreach of the optical elements.
 9. The lighting assembly of claim 1,wherein the first leading surface and the first trailing surfaceintersect to form a ridge.
 10. The lighting assembly of claim 9, whereinthe ridge is arcuate and intersects the first major surface or thesecond major surface at which the optical element is positioned at itsends.
 11. The lighting assembly of claim 1, wherein the first leadingsurface and the first trailing surface are connected by a first roundedsurface that is tangential to the first leading surface and to the firsttrailing surface.
 12. The lighting assembly of claim 11, wherein therounded surface is arcuate and intersects the first major surface or thesecond major surface at which the optical element is positioned at itsends.
 13. The lighting assembly of claim 1, wherein the optical elementsof the first set are indentations in a first major surface or the secondmajor surface of the light guide.
 14. The lighting assembly of claim 1,wherein the optical elements of the first set are protrusions from thefirst major surface or the second major surface of the light guide. 15.The lighting assembly of claim 1, wherein: the optical elements of thefirst set are nominally identical to one another in shape, the opticalelements of the second set are nominally identical to one another inshape, and the optical elements of the first set are different from theoptical elements of the second set.
 16. The lighting assembly of claim1, wherein the first included angle differs from the second includedangle by 5° or more.
 17. The lighting assembly of claim 1, wherein theoptical elements of the first set are micro-optical elements.
 18. Thelighting assembly of claim 1, wherein light output from the lightingassembly has a combined light ray angle distribution, the combined lightray angle distribution being a combination of the first light ray angledistribution and the second light ray angle distribution, and thecombined light ray angle distribution in the measurement plane issignificantly narrower than an omnidirectional output distribution. 19.The lighting assembly of claim 1, wherein the lighting assembly isconfigured as one of an under-cabinet lighting fixture, an LED lamp, ora ceiling fixture.